failed to find any directx 9.0c compatible graphics adaptors in this system. Make sure you have direct x 9.0c compatible graphics adaptor and you have installed the latest drivers provided by your manufacturer.

Before I answer your question below, I must apologize for missing a key point in your first post.
You have a Gateway 400 VTX, and ONLY 256 MB of memory.

What you really need to get it working is a memory upgrade.

You have 256 MB of onboard installed memory.

You need two modules of 512 MB DDR PC2700 memory... one in each slot. Give your 256 MB module away, if you want to run games on that laptop.

Now, if you want to upgrade the drives, you will also need the memory upgrade.

Since you are using Windows XP Home, you can go to Start->Control Panel->System->Hardware->Device manager, and disable or remove the old device/Drivers only.
Before you do this, though, get the current and most recent drives, and download them to a place on your computer where you can find them later.
Then when you disable or remove the old drivers, reboot, then go to the location where you have stored the new drivers and install them. Read the instructions from the website of the manufacturer carefully as installing some drivers is tricky... I would write them down or print them out.

There are plenty of sites for the DDR PC2700 laptop memory... Crucial.com, Kahlon.com, TigerDirect.com, Zipzoomfly.com, NewEgg.com, and my recommendation, www.directron.com.
It is not diffcult to replace. You need a screwdriver to remove the memory cover on the bottom of your laptop, then carefully while wearing rubber gloves or plastic bags, unseat the clips on each side of the slot and pull out the old memory modules directly out being careful not to force anything.
Then insert the new modules, and be sure the clip is back in position.